The present disclosure relates to a touch operation device which recognizes an input pattern so as to release lock state and an image forming apparatus which includes such a touch operation device. The present disclosure also relates to a method of recognizing an input pattern so as to release lock state.
There are electronic devices which have lock mechanisms for preventing the operations of persons who are not authorized and other people (unauthorized use). Lock mechanisms which use characters (password) are conventionally known. In recent years, electronic devices which include touch panels have been increasingly available. In the electronic devices which include touch panels, the lock mechanism of a pattern lock method is increasingly adopted. In the pattern lock method, a trace (pattern) which is obtained by tracing points displayed on the touch panel is checked against a previously registered pattern, and when they agree with each other, the lock state is released.
In this method, when the lock state is released, a user draws a pattern on the touch panel with a finger. Hence, a drawing mark caused by the sebum of the finger or the like may be left on the touch panel. Based on the drawing mark, a person who is not authorized to use the electronic device may release the pattern lock.
An electronic device is proposed which can prevent a drawing mark from being left on a touch panel. In this electronic device, the touch panel is used which detects (reacts with) a finger of a user without making contact therewith. In a state where the finger is separated from the touch panel, a drawn pattern is recognized. With the touch panel which can detect the finger of the user in a noncontact manner, the fingerprint of the finger of the user and the sebum of the finger are not left (drawing mark is not left). In this electronic device, the lock state is unlikely to be released by a person (unauthorized) who do not know the pattern.
However, in the electronic device described above, the position and the direction of the pattern on the touch panel are constantly the same. A release pattern for the lock state can be estimated from the movement of the finger of the user when the pattern is input. A person who is not authorized may release the lock state.